The purpose of this study is to examine the effect of extracorporeal circulation on protein metabolism. A catabolism of body protein has been shown to accompany surgery. The loss of protein depends on the degree of trauma and is associated with a depression of muscle protein synthesis. Coronary artery bypass surgery traditionally has been performed with the assistance of cardiopulmonary bypass (extracorporeal circulation), which has been suggested to exacerbate the catabolic response. Recently new surgical advancements have allowed for the same surgery to be performed on the beating heart, without the use of cardiopulmonary bypass. It is not known whether this new procedure ameliorates the detrimental effect on protein synthesis. Patients who undergo either technique for cardiac revascularization will have their protein synthesis assessed. In addition, circulating levels of certain stress hormones (glucagon, cortisol, epinephrine), cytokines (tumor necrosis factor, interleukin-1, interleukin-6, interleukin-8, and interleukin-10), and acute phase reactants (C-reactive protein) will be measured and correlated to changes in protein metabolism.